Alright, welcome back to A Glimpse of Engineering. I'm Caleb Thompson, and as always, I'm joined by Emily Cartwright. Today, we're diving into the nuts and bolts of switchboard design—specifically, compliance and construction. Emily, you ready to get technical?Always, Caleb. This is the stuff that keeps me up at night—in a good way. So, let's start with the big one: AS/NZS 61439. If you're working on boards over 125 amps or with a fault level of 10kA or more, compliance with this standard isn't just a nice-to-have—it's mandatory. No wiggle room.Yeah, and I remember when I first started poking around in this space, I thought, "How different can one standard be from another?" Turns out, 61439 is a whole ecosystem. It's not just a checklist—it's a series, right?Exactly. There's part 1, which covers general rules, and then you’ve got specific parts for different assemblies—like part 2 for power switchgear, part 3 for distribution boards, and so on. The key thing is, if you’re above that 125A or 10kA threshold, you have to build and verify your assemblies to this standard. It’s called up by law in WA, so if you skip it, you’re not just risking a slap on the wrist—you could be looking at serious penalties.And it’s not just about ticking boxes. As we talked about in earlier episodes, especially when we covered the design process, compliance is about safety, reliability, and making sure the thing actually works when it matters. OFI’s approach is pretty robust, isn’t it?Yeah, OFI’s got a whole system for this. They use verified assemblies—so, ELSTEEL and CUBIC are the main ones. That means the base design is already tested and compliant, which makes life a lot easier. But you still have to make sure any changes or customizations don’t break compliance. That’s where the real work starts.So, if you’re listening and thinking, “I’ll just swap out a breaker or two, no big deal”—nah, it’s a big deal. The standard is there for a reason. And, as we’ve seen, the consequences for getting it wrong can be pretty severe.Right, so let’s talk about design verification. OFI’s approach is to stick with those verified assemblies as much as possible. If you use ELSTEEL or CUBIC and follow their instructions, you’re already most of the way there. But the moment you start making changes—like, say, using a different breaker or modifying the enclosure—you have to verify that the whole assembly still meets 61439.And that’s not just a paperwork exercise, is it? There’s actual engineering assessment involved. You’ve got to check if the modification affects things like heat rise, clearances, or even the structural integrity of the board. It’s a bit like, uh, changing the engine in a car—you can’t just drop in any old motor and expect it to run the same.Yeah, that’s a good analogy. And the process is pretty structured. OFI uses section 10 of 61439.1 to check compliance. If there’s a risk the change could impact performance, you have to do a new verification. That might mean extra testing or documentation. And after the board’s built, you need to verify it against the original design checklists—ideally right after FAT, before it leaves the workshop.So, the lesson is: stick to the manufacturer’s recommendations as much as you can. The more you deviate, the more work you create for yourself—and the more risk you take on. I think we touched on this in our last episode about design reviews, but it’s worth repeating. Peer reviews and SME checks are your friends here.Absolutely. And it’s not just about ticking off a list. You’re making sure the board is safe, reliable, and actually fit for purpose. That’s what keeps the lights on—and keeps people safe.Alright, so let’s say you do have to make a change—maybe the client wants a different brand of breaker, or you need to fit something in a tight space. How do you manage those deviations?That’s where Annex D comes in. It’s basically a checklist in the standard that helps you assess whether your modified assembly is still compliant. You go through each item—like temperature rise, dielectric properties, short-circuit withstand, all that—and document how you’re verifying compliance for each one.So, it’s not just a “she’ll be right” approach. You’ve got to be methodical. And if you can’t verify something—like, say, you don’t have test data for a new component—you might need to do extra testing or get documentation from the supplier.Exactly. And all of that needs to be documented for the client. If you’re making changes, you need to show your work—how you verified compliance, what methods you used, and so on. It’s a bit of a pain sometimes, but it’s what keeps everyone honest. And if something goes wrong down the track, you’ve got a clear record of what was done and why.And I guess that’s where the lessons learned from previous projects come in handy. If you’ve seen a particular deviation cause issues before, you know to watch out for it. It’s like building up a playbook over time.Yeah, and OFI’s pretty good at capturing those lessons. They use design registers and checklists to make sure nothing slips through the cracks. It’s not glamorous, but it’s what makes the difference between a good project and a disaster.Let’s shift gears a bit and talk about the physical side—the frame and enclosure design. OFI mainly uses CUBIC and ELSTEEL modular boards, right?Yeah, those are the go-tos. Each has its own workflow. For CUBIC, you use their software to build up the frame and select modules, inserts, and busbars. There’s a guide—actually, it’s a bit of a monster document, but it’s got everything you need. You’ve got to pay attention to things like rated current, fault level, and power loss for each module.And for ELSTEEL, it’s a bit different, isn’t it? You’ve got to check their reference list to make sure the breakers and other components you want to use have actually been tested in their system. If it’s not on the list, you might have to reach out to ELSTEEL or check their website for updates.Exactly. And once you’ve picked your components, you fill out a checklist and send it off for procurement. Both systems have their quirks, but the main thing is to follow the workflow and use the technical support available. If you try to wing it, you’ll end up with a board that doesn’t fit or, worse, isn’t compliant.And I guess that’s where the procurement checklist comes in. Make sure you’ve got all the right parts, and double-check before you start building. Saves a lot of headaches down the line.Yeah, and don’t forget to document everything. If you ever need to go back and figure out why something was done a certain way, having that paper trail is a lifesaver.Alright, so you’ve done all the design work, picked your modules, and checked compliance. What’s next? How do you get from CAD to actual construction?This is where the rubber hits the road. Before you can start fabrication, you need a full set of design outputs—general arrangement drawings, single line diagrams, cable schedules, BOMs, and all the compliance documentation. It’s not just about pretty drawings; it’s about making sure the workshop has everything they need to build the board right the first time.And I’ve seen what happens when something’s missing. You get delays, rework, and a lot of grumpy people in the workshop. OFI’s got a pretty tight integration between the design team and the workshop, don’t they?Yeah, they do. They use 3D models—Fusion 360, mostly—to help the workshop visualize the design and spot any issues before fabrication starts. Plus, all the parts lists and drawings are linked to the product repository, so there’s less chance of using the wrong component. It’s a bit of extra work up front, but it pays off in fewer mistakes and smoother builds.And I love that they keep a library of practical examples—so if you’re stuck, you can look up how a similar board was built before. It’s like having a cheat sheet, but for grown-up engineers.Yeah, and it’s not just for the designers. The workshop team can feed back issues or improvements, so the next project gets a bit better. It’s that continuous improvement loop we talked about in earlier episodes—always learning, always refining.Alright, I think that’s a good place to wrap up. Next time, we’re going to get even more hands-on with “Building Low Voltage Assemblies.” Emily, as always, thanks for sharing your expertise—and your war stories.Thanks, Caleb. Always a pleasure. And thanks to everyone listening—if you’ve got questions or want us to dig into a specific topic, let us know. See you next time.Catch you all soon. Stay safe, and keep building smarter.

Episodes

Switchboard Design – Compliance and Construction